Polymethylene-bis-benzothiazolium salts



United States Patent POLYMETHYLENE-BIS-BENZOTHIAZOLIUM SALTS Charles F. H. Allen and Charles V. Wilson, Rochester,

N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application October 17, 1951, Serial No. 251,839

1 Claim. (Cl. 260304) This invention relates to polymethylene-bis-benzothiazolium salts and a method for making them.

A number of quaternary salts containing heterocyclic nuclei are useful in supersensitizing photographic silver halide emulsions. See, for example, Carroll et al. U. S. Patent 2334,864. issued November 23, 1943. The biscompounds, or double-enders, are particularly useful for this purpose because of their tendency to be nonwandering. Allen et al. U. S. Patent 2,500,110, issued March 7, 1950, describes bis-pyridyl quaternary salts which can be used to advantage to supersensitize photographic silver halide emulsions optically sensitized with a sensitizing dye.

We have now found new bis-benzothiazolium salts which can advantageously be used as antifoggants for photographic silver halide emulsions, rather than as supersensitizers for photographic silver halide emulsions.

It is, therefore, an object of our invention to provide polymethylene-bis-benzothiazolium salts. Another object is to provide a method for making such quaternary salts. Other obiects will become apparent from a consideration of the following description and examples.

Polvmethylene-bis-benzothiazolium quaternary salts containing a reactive group, such as methyl, in the 2-position have been previously described in Wilson U. S. Patent 2,425.774, issued August 19, 1947. The quaternary salts of Wilson are useful as intermediates in the preparation of polymeric cyanine dyes, although they are not particularly efficacious as antifoggants. The quaternary salts of the instant invention are especially useful as antifoggants for photographic silver halide emulsions.

According to our invention, we provide new polymethylene-bis-benzothiazolium salts by a process which comprises heating together a benzothiazole base with an alkylene halide.

Typical benzothiazole bases include those represented by the following general formula:

wherein Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzothiazole series. Especially useful is benzothiazole itself, and benzothiazoles containing a substituent on the benzene ring of the benzothiazole nucleus, such as alkyl. aryl, alkoxvl, halo en, hydroxvl, etc. Typical are benzothiazole. 6-methoxybenzothiazole, G-ethoxybenzothiazole, S-phenylbenzothiazole, 6-phenylbenzothiazole, 5-chlorobenzothiazole, 6-chlorobenzothiazole, S-hydroxybenzothiazole, S-methylbenzothiazole, 6-methylbenzothiazole, S-ethylbenzothiazole, etc.

Typical alkylene halides include those represented by the following general formula:

wherein X1 represents a halogen atom, such as chlorine, bromine, etc. and n represents a positive integer of from 1 to 9. Particularly useful are the alkylene bromides.

The temperature used can be varied, depending on the particular reactants. In general, temperatures of from about 5 C. to 150 C. can be used. In general, about two molecular equivalents of the benzothiazole base (Formula I) are employed to each molecular equivalent of the alkylene halide (Formula II). The polymethylene- 2,694,716 Patented Nov. 16, 1954 ICC bis-benzothiazolium salts thus produced can be represented by the following general formula:

wherein Z, X1, and n have the values set forth above. The halide anion (X1 above) can be replaced by other anions by usual double decomposition procedures. It is thus possible to produce polymethylene-bis-benzothiazolium salts of the following general formula:

Example 1.Ethylene-bis-benzothiazolium perchlorate CH HC N-CH2CH2N A mixture of 5.4 parts of benzothiazole and 3.8 parts of ethylene bromide was heated for 20 hours at C. On cooling, the mixture set to a glass that was broken up by treatment with hot methanol. In this way 3 parts of an orange colored solid was obtained, which was essentially ethylene-bis-benzothiazolium bromide. The material dissolved in water to give a deep red solution which was decolorized to yellow with a decolorizing carbon (Nuchar). By treatment of an aqueous solution of this bromide with an aqueous solution of sodium perchlorate, ethylene-bis-benzothiazolium perchlorate was formed as a pale yellow crystalline solid.

Example 2.-Trimethylene-bis-benzothiazolium perchlorate -S\ /S OH HC chlorate. On cooling to room temperature, 10.5 parts of trimethylene-bis-benzothiazolium perchlorate separated.

Example 3 .Hexamethylene-bis-benzothiazolium perchlorate In a procedure similar to Example 2, 9 parts of hexamethylene bromide and parts of "benzothiazoleheated' Example 4.'Pentamethylene-bis-benzothiazolium perchlorate M CH 110 A mixture of 2.7 parts ofbenzothiazole and 2.3 parts of pentamethylene bromide was heated for 3 hours at 135 C. The glassy solid resulting on cooling was dissolved in 40-50 cc. of methanol. The warm methanol solution of the reaction product, which was essentially pentamethylene-bis-benzothiazolium bromide, was treated with a solution of 5 parts of sodium perchlorate in 8 parts of warm water. Pentamethylene-bis-benzothiazolium perchlorate (-3 parts) separatedimmediatelyas a yellowish granular product. The material had only slight solubility in water and alcohol. It was recrystallized from a large volume of methanol. It' formed pale yellow needles melting at about 208 C.

Example 5 .Heptamethylene-bis-benzothiazolium perchlorate \OH HC/ Heptamethylene bromide (5.2 parts) and benzothiazole (5.4 parts) were mixed and heated for hours at 130 C. with stirring. The resulting product'was worked up as set forth in Example 2, 10 parts of sodium perchlorate being used to form the. heptamethylene-bis-benzothiazolium perchlorate. The crude product (7.5 parts) was recrystallized from methanol to give a material that melted at l78-180 C.

Example 6.Nonamethylene-bis-benzothiazolium perchlorate Example 7.Decamethylene-bis-benzothiazolium perchlorate A mixture of 10 parts of decamethylene bromide and 9 parts of benzothiazole was heated at 120-130 C. for two hours. The reaction mixture was dissolved in about 100 parts of methanol. The hot methanolic solution was treated with a decolorizing carbon and filtered. To the filtrate was added an excess of an aqueous solution of sodium perchlorate. There was immediate precipitation of a yellow solid which is essentially decamethylene-bisbenzothiazolium perchlorate. The yield was 12.5 parts.

Example 8.Decamethylenebis-6-methoxybenzothiazoliam perchlorate CH HC Example 9.Ethylene-bis (oxyethoxymethylbenzothiazolium perchlorate) Ethylene-bis (oxyethoxymethyl chloride) (3.7parts) in dry benzene (5 parts) was added dropwise to a solution of benzothiazole (4.4 parts) in benzene. Thereaction was carried out at5-15 C. The produce separated in tacky form. It was taken up in cold water; the aqueous layer was separated from the benzenelayer and washed with ether. This aqueous solution was added to an excess of sodium perchlorate in water. Ethylenebis-(oxyethoxymethylbenzothiazolium perchlorate) separated as an oil from which the aqueouslayerwas decanted. The oil was washed with cold water and after standing became solid. The solid was stirred with ether and then collected-on a filter. The yield was 2.1 parts. The melting point was 7893 C. It was recrystallized from a mixture of methanol and acetone by the addition cfgse tlaer. The product thus obtained melted at 134- Example 10. Decamethylene-bis-oxymethylbenzolhiazolium perchlorate S\ HC/S HaCO- OCH;

To a solution of 8.8 parts of benzothiazole in 35 parts of dry benzene was added (dropwise) 81. parts of decamethylene-bis-oxymethyl chloride in 10 parts of benzene. The gelatinous material that separated was dissolved by the addition of 50 partsof cold water. The aqueous layer was separated from the benzene layer and washed with ether to remove any unchanged starting materials. The aqueous solution of decamethylene-bis- (oxymethylbenzothiazolium chloride) was added to an excess of sodium perchlorate in 10 parts of water. An oily precipitatewhich solidified on standing was formed. It was collected on a filter, Washed with cold water and then with acetone. In this manner-4.7 parts of crude decamethylene bis oxymethylbenzothiazolium perchlorate, melting at l25-133 C. was obtained. It was recrystallized from methanol. By such treatment it separated in long white needles, melting at l30132 C.

In lieu of using bases of Formula I above wherein Z represents the non-metallic atoms to complete a heterocyclic nucleus of the benzothiazole series, we have prepared bis-quaternary salts using bases of 'Formula I above wherein Z represented the non-metallic. atoms necessary to complete a ditferent nucleus,,such as benzimidazole, quinoxaline, Z-methylimidazoline, acridine, and .cinnoline, however, the bis-quaternary salts thus produced. do not provide the advantages which are. realized when using the bis-benzothiazolium.salts of our invention. The-instant bis-benzothiazolium salts are also useful as adju- 5 6 vants to mixes-gain tfihotogrzlphic silver halide ferlrgiul- References Cited in the file of this patent sions as descri e in e copending app ication o urt H. Carroll, S. N. 251,833, filed on even date herewith UNITED STATES PATENTS (now U. S. Patent 2,673,149, issued March 23, 1954). Number Name Date What we claim as our invention and desire secured 5 2,393,351 Wilson Jan. 22, 1946 by Letters Patent of the United States is: 2,425,774 Wilson Aug. 19, 1947 The compound represented by'the following formula: 2,515,913 Zandt et a1. July 18, 1950 s s FOREIGN PATENTS OH H0 10 Number Country Date I 402,458 Great Britain Dec. 4, 1933 III-OHzCHzCHq-N C104 1104 

